The present invention relates to a disk drive for carrying out data writing/reading operations onto and from a disk such as a flexible magnetic disk and a magnetooptic disk.
1. Field of the Invention
A magnetic disk drive as one of various types of disk drives comprises a head carriage movably holding a magnetic head for carrying out data writing/reading operations onto and from a magnetic disk, a moving mechanism for moving the head carriage in a predetermined radial direction with respect to the magnetic disk, a disk table for holding and rotating the magnetic disk, a rotation drive mechanism for driving the disk table, and a loading mechanism for loading and unloading the magnetic disk through a disk slot onto and from the disk table, respectively. The magnetic disk drive further comprises a main printed wiring board with various circuit components mounted thereon, a subsidiary printed wiring board with the rotation drive mechanism and the disk table mounted thereon, and a frame plate to which the main and the subsidiary printed wiring boards are attached.
The frame plate is typically formed by die-casting an aluminum material taking its mechanical strength into consideration. However, it is a recent trend to form the frame plate by pressing an iron plate. The frame plate made of the iron plate must be as thick as 1-1.2 mm in order to assure sufficient mechanical strength. This imposes a limitation upon reduction in weight.
2. Description of the Related Art
Referring to FIG. 1, a conventional magnetic disk drive will be described. The magnetic disk drive comprises a frame plate 11 and a cover member 12 made of a thin metal plate covering the frame plate 11. A combination of the frame plate 11 and the cover member 12 forms a hollow receiving space for receiving a magnetic disk (not shown). The magnetic disk has an access region for data write/read operations which are carried out when the magnetic disk is received in the receiving space.
In front of the receiving space, a front bezel 13 is assembled to guide the magnetic disk into the receiving space in a proper attitude. The front bezel 13 has a slot 13a. In the receiving space, an ejection plate 14 and a disk holder unit 15 are arranged. When the magnetic disk is inserted into the receiving space through the slot 13a, the magnetic disk is held by the disk holder unit 15 at a predetermined position with its lower and upper surfaces faced to the election plate 14 and the disk holder unit 15, respectively.
A head carriage 16 and an ejection lever 18 are also arranged in the receiving space. The head carriage 16 has a magnetic head 17 to be faced to a window of the magnetic disk when the magnetic disk is located at the predetermined position. The ejection lever 18 has a rotation shaft 18a pivotally supported on the frame plate 11 and an arm 18b extending from the rotation shaft 18a in one direction. The ejection lever 18 is urged by an ejection lever spring 18c and is rotatable around the rotation shaft 18a in a plane parallel to the surface of the frame plate 11.
On the frame plate 11, various mechanical components are mounted in addition to the ejection lever 18 and the head carriage 16. Specifically, those mechanical components include a disk table 19 for rotating the magnetic disk, a stepping motor 20 for moving the head carriage 16 back and forth, a guide bar 21 for guiding the movement of the head carriage 16, and a guide bar clamp 22 for clamping the guide bar 21. To the lower or rear surface of the frame plate 11, a main printed board and a subsidiary printed board as components of the magnetic disk drive are fixed through screws, although not shown in the figure. On the main printed wiring board, electric circuit components for data writing/reading operations are mounted. On the subsidiary printed wiring board, a motor for rotating the disk table 19 and a drive circuit for driving the motor are mounted. The main and the subsidiary printed wiring boards are covered with a lower cover member (not shown).
When an ejection button 23 protruding outside of the front bezel 13 is slightly depressed into the receiving space, the ejection plate 14 slightly moves backward to rotate the ejection lever 18.
The magnetic disk itself received in the receiving space is locked by a locking mechanism (not shown) to be prevented from undesirably escaping from the receiving space. The lock of the magnetic disk by the locking mechanism is released when the ejection button 23 is pushed. In this event, the ejection lever 18 is rotated by the urging force of the ejection lever spring 18c to push the magnetic disk. As a result, the magnetic disk is ejected from the receiving space to partially protrude outward through the slot 13a formed in the front bezel 13. The ejection plate 14 has an ejection spring 14a as a spring mechanism. When the ejection button 23 is released from the depressing force, the election plate 14 is forced by the ejection spring 14a to return to its original position. Thus, the magnetic disk can be taken out from the receiving space.
As is obvious from the foregoing, the magnetic disk drive has a structure in which the mechanical components for data writing/reading operations are arranged on the upper or principal surface of the frame plate 11 while the electric circuit components on the printed wiring boards are arranged on the lower surface.
The frame plate 11 is typically formed by die-casting an aluminum material, taking its mechanical strength into consideration. However, it is a recent trend to form the frame plate by pressing an iron plate. The frame plate made of the iron plate mast be as thick as 1-1.2 mm in order to assure sufficient mechanical strength. This imposes a limitation upon reduction in weight.